Which edge of this map is north?
top
right side
bottom
left side

True North on a map is the direction of a line of longitude which converges on the North Pole. The grid lines on Ordnance Survey maps divide the UK into one kilometre squares, east of an imaginary zero point in the Atlantic Ocean, west of Cornwall. The grid lines point to a Grid North, varying slightly from True North.

Ais 190 b is 200c it can't be more then 100%